How to measure ring size at home (US, UK, AU, EU)
You can measure your ring size at home in two ways: across the inside of a ring that already fits, or with a strip of paper wrapped round your finger. The inside diameter gives a US size: 11.63 mm plus 0.8128 mm per size, so 16.5 mm is a US 6. The strip's length, the circumference in millimetres, is the EU size. UK and Australian sizes are letters.
3D Jewelry Designer2 min read
How do you measure a ring that already fits?
- Pick a ring that fits the finger you are sizing and is still round.
- Lay it on a millimetre ruler and measure across the inside, edge to edge, at the widest point.
- Convert the diameter to a US size:
US size = (inside diameter in mm − 11.63) ÷ 0.8128
17.3 mm across: (17.3 − 11.63) ÷ 0.8128 = 6.98, so a US 7How do you measure your finger with paper?
- Wrap a narrow strip of paper round the base of the finger, snug but not tight.
- Mark where the end overlaps, flatten the strip and measure from the end to the mark.
That length is the circumference in millimetres, which is the EU size: 54 mm is an EU 54. Divide it by π (about 3.14) for the diameter, or use the table below.
Which size does your measurement give?
| US size | Inside diameter (mm) | EU size (inside circumference, mm) |
|---|---|---|
| 5 | 15.7 | 49.3 |
| 6 | 16.5 | 51.9 |
| 7 | 17.3 | 54.4 |
| 8 | 18.1 | 57.0 |
| 9 | 18.9 | 59.5 |
| 10 | 19.8 | 62.1 |
Half a US size is only about 0.4 mm across the ring, or 1.3 mm round the finger, so read the ruler closely and measure twice. The ring size converter has the full chart.
How do you find a UK or Australian size?
UK sizes are letters, and Australia and New Zealand use the same ones. They start at A, about a US ½, and step roughly half a US size per letter. The converter turns your diameter or EU size into the nearest letter. Charts round between letters in different directions, so check yours on a jeweller's ring gauge. For more on the systems, see ring size and ring size charts explained.
How do you get an accurate reading?
- Measure late in the day. Fingers tend to swell as the day goes on, and they shrink in the cold.
- Size the right finger. The same finger on your other hand can differ.
- Mind the knuckle. The ring has to slide over it. If it is wider than the base of the finger, measure both and pick a size between them.
- Allow for the band. A wide band sits tighter than a narrow one at the same size.
Can a camera estimate your ring size?
Yes, roughly. On the live camera, virtual ring try-on shows a size estimate in US, UK and EU sizes, with its range, after a few seconds with your palm flat to the camera. A camera cannot measure an exact size, so treat it as a cross-check. Once you have measured, tap the size chip and enter your size.
Try it free in the ring try-on; nothing from the camera leaves your device. The AR try-on guide covers the details.
Questions
Can I use string instead of paper?
Only if it does not stretch. Stretchy string changes length between wrapping and measuring, so paper gives a steadier reading.
What if I am between two sizes?
Choose the larger one, especially for a wide band, and confirm it on a jeweller's ring gauge.
Related
- Ring Size Converter: US, UK, AU, EU and mm Chart
Convert ring sizes between US, UK and Australian letters, EU and millimetres, with a full printable chart.
- Ring size: what US, UK and EU sizes measure
A ring size describes the inside of the band. US sizes step along the inner diameter, EU sizes are the inner circumference in mm, and UK sizes are letters.
- Virtual ring try-on for your store
Let shoppers try a ring on from your product page by live camera, hand photo or model hand, with a ring size estimate and no app to install.